1. Field of Invention
The present invention relates to a blood pressure monitoring apparatus used in the fields where the continuous blood monitoring for the patient is required in the operation room, the intensive care unit, the emergency treatment room, or the artificial dialysis treatment room.
2. Related Art
Conventionally, the blood pressure monitoring apparatus for monitoring the blood pressure of the subject by measuring the blood pressure of the subject continuously is well known in which a cuff is wound around an upper arm portion or the like of the subject to make the noninvasive blood pressure measurement by an oscillometric method, or the artery of the subject is punctured to make the invasive blood pressure measurement.
By the way, the conventional blood pressure monitoring apparatus had the following disadvantages.
That is, (a) the blood pressure monitoring apparatus for making the noninvasive blood pressure measurement with the cuff often left unnoticed a sudden change in blood pressure due to a shock, when the measurement interval was long, for example, five minutes or more, in the periodic NIBP measurement. To cope with this situation, the measurement interval may be shortened to one minute, for example, to lessen the oversights of sudden change in blood pressure. However, when the measurement interval is shorter, some load may be exerted on the portion with the cuff wound.
(b) in the periodic NIBP measurement, the patient may undergo frequent tightness of the cuff with pressure more than necessary.
And (c) with the blood pressure monitoring apparatus for making the invasive blood pressure measurement, the subject may be spiritually affected by the invasion. Also, it takes more time than the noninvasive blood pressure measurement, and imposes more burden on the medical stuff.
Thus, it is an object of the present invention to provide a blood pressure monitoring apparatus that can monitor the blood pressure safely and with high accuracy in continuous manner, without giving load on the subject.
According to a first aspect of the present invention, there is provided a blood pressure monitoring apparatus comprising blood pressure measuring means for measuring the blood pressure employing a cuff, pulse wave propagation parameter measuring means for measuring the pulse wave propagation parameter, hemodynamics measuring means for measuring the hemodynamics, and control means for controlling the blood pressure measuring means on the basis of a change in pulse wave propagation parameter measured by the pulse wave propagation parameter measuring means and a change in hemodynamics measured by hemodynamics measuring means, wherein the control means controls the blood pressure measuring means to measure the blood pressure on the basis of the amount of change and discriminated change trend in the pulse wave propagation parameter measured by the pulse wave propagation parameter measuring means, and the amount of change and discriminated change trend in the hemodynamics measured by the hemodynamics measuring means.
According to a second aspect of the invention, there is provided the control means controls the blood pressure measuring means on the basis of a comparison between a pulse wave propagation parameter change threshold memorized to monitor the amount of change in the pulse wave propagation parameter and the amount of change in the pulse wave propagation parameter measured by the pulse wave propagation parameter measuring means and a comparison between a hemodynamics change threshold memorized to monitor the amount of change in the hemodynamics and the amount of change in the hemodynamics measured by the hemodynamics measuring means.
According to a third aspect of the invention, there is provided the blood pressure monitoring apparatus, wherein the control means updates the pulse wave propagation parameter change threshold.
According to a fourth aspect of the invention, there is provided a blood pressure monitoring apparatus comprising blood pressure measuring means for measuring the blood pressure employing a cuff, pulse wave propagation parameter measuring means for measuring the pulse wave propagation parameter, hemodynamics measuring means for measuring the hemodynamics, and control means for controlling the blood pressure measuring means on the basis of a change in pulse wave propagation parameter measured by the pulse wave propagation parameter measuring means and a change in hemodynamics measured by the hemodynamics measuring means, wherein the control means compares between a pulse wave propagation parameter change threshold memorized to monitor the amount of change in pulse wave propagation parameter and the amount of change in pulse wave propagation parameter measured by the pulse wave propagation parameter measuring means and detect the change trend in the measured pulse wave propagation parameter, compares between a hemodynamics change threshold memorized to monitor amount of the change in the hemodynamics and the amount of change in hemodynamics measured by the hemodynamics measuring means, detects the change trend in the hemodynamics measured, and updates the pulse wave propagation parameter change threshold on the basis of the results of two comparisons with the thresholds and the detected change trends.
According to a fifth aspect of the invention, there is provided the blood pressure monitoring apparatus, wherein the control means controls the blood pressure measuring means to measure the blood pressure on the basis of a comparison between the updated pulse wave propagation parameter change threshold and the pulse wave propagation parameter measured by the pulse wave propagation parameter measuring means.
Further, according to a sixth aspect of the invention, there is provided the blood pressure monitoring apparatus, wherein the hemodynamics measuring means measures at least one of a heart rate, a pulse wave amplitude, and a DC component of pulse wave, and the control means controls the blood pressure measuring means on the basis of at least one of the heart rate measured, the pulse wave amplitude, and the DC component of pulse wave.
Furthermore, according to a seventh aspect of the invention, there is provided the blood pressure monitoring apparatus, wherein the control means controls the blood pressure measuring means on the basis of a pulsation rate fluctuation rate calculated from the changes in the amplitude of pulse wave and the DC component of pulse wave measured by hemodynamics measuring means.
And according to an eighth aspect of the invention, there is provided the blood pressure monitoring apparatus, wherein the control means updates the pulse wave propagation parameter change threshold on the basis of at least one of the change in pulse wave propagation parameter, the change in heart rate, and the pulsation rate fluctuation rate.